1. Field of the Invention
The present invention relates in general to an apparatus for processing crankpins of a crankshaft with burnishing rollers. More particularly, it relates to such an apparatus for effecting roll finishings upon fillets formed on crankpins of a crankshaft.
2. Description of the Prior Art
It is generally known that fillets formed on crankpins and journals of crankshafts for automotive internal combustion engines are processed by burnishing rollers for an increased strength against fatigue. A known fillet rolling apparatus of this type is provided with a pair of master crankshafts each having the same shape as blank crankshafts to be given roll finishings, as disclosed for example in Japanese Patent Application No. 54-117849 laid open for public inspection. In the known apparatus, plural pairs of roller holders respectively arresting crankpins of a blank crankshaft are moved to trace the rotational loci of associated crankpins of the master crankshafts. Such tracing motion of each pair of the roller holders causes burnishing rollers carried on the roller holders to turn on their respective axes as well as to revolve round a corresponding crankpin of the blank crankshaft, whereby fillets of each crankpins of the blank crankshaft can be given roll finishings.
However, using the master crankshafts, the prior art fillet rolling apparatus is incapable of processing other blank crankshafts than those which have the same shape as the master crankshafts. That is, blank crankshafts which differ from the master crankshafts in crankpin stroke or in respective orientations of crankpins cannot be processed even when the roller holders are replaced with those prepared therefor.